1. Field of the Invention
The present invention relates to a film or sheet holding apparatus for setting a film or sheet disposed on a panel-shaped resin injection molded product within an injection mold for the purpose of protecting or decorating the surface of the resin molded product, or other purposes in the case where, for example, the panel-shaped resin molded product is injection-molded.
2. Description of the Related Art
Up to now, for example, in a vehicle window for an automobile, in order to make the vehicle light in weight, there has been known a lighting member made of a resin that is smaller in specific gravity than glass. However, there arises such a problem that the surface of the resin window is liable to be damaged when it is brought into physical contact with another substance. To prevent the above problem, the surface of the resin window is protected by coating a hard coat layer thereon, for example, by coating a protective film with a hard coat that is high in abrasion resistance from the viewpoint of protecting the quality of the resin window.
The above resin window is molded by insert molding. That is, as shown in FIG. 7, a molten resin is injected into a cavity 102 in a state where a protective film 103, which has been cut in a size corresponding to the shape of the resin window to be molded in advance, is set on one inner mold surface (or both of inner mold surfaces) of two coupled-type injection molds 101 having vertical coupled surfaces thereof, whereby the surface of the resin window is coated with the protective film 103 simultaneously upon being molded. In this situation, in the event that the surface of the resin window is coated with the protective film 103 identical shape with or smaller in shape than the surface of the resin window as shown in the figure, the protective film 103 is held within the cavity 102.
Under the above circumstance, up to now, as means for holding the protective film 103 on the mold surface of the injection mold 101, as shown in FIG. 8, the protective film 103 is adsorbed and held by a plurality of vacuum holes 105 disposed laterally with respect to two positioning pins 104 that are located on an upper edge side of the mold surface (a resin filling inlet side) in a state that an upper edge portion of the protective film 103 is hung on those positioning pins 104.
Note that the small holes of the protective film 103, which correspond to the positioning pins 104, are so formed as to be larger in diameter than the positioning pins 104 with a margin, taking into consideration the expansion of the protective film 103 due to temperature, a manufacturing variation and the efficiency of working. For that reason, there is a case in which a floating 103a may be produced on the molded surface of the protective film 103, as shown in FIG. 9A, when the protective film 103 is adsorbed by the vacuum holes 105 after the upper end portion of the protective film 103 is hung on the positioning pins 104. Also, as shown in FIG. 9B, there is a possibility that a peeling 103b from the positioning pins 104 is produced on a portion apart from the vacuum holes 105 after the protective film 103 is adsorbed and before closing mold, or before the molten resin is injected.
When the floating 103a or the peeling 103b occurs, there arises such a problem that the molten resin goes to a front surface side of the protective film 103 beyond the portions of the floating 103a or the peeling 103b during an injection molding process, resulting in a defective.
The present invention has been made in view of the above problems inherent in the conventional apparatus, and therefore has an object to provide a film or sheet holding apparatus for an injection mold which is capable of surely holding a film or sheet at a specific position of a mold surface of the injection mold.
In order to achieve the above object, according to the present invention, there is provided a film or sheet holding apparatus for an injection mold for holding a film or sheet on a mold surface of the injection mold consisting of two coupled molds having substantially-vertical coupled surfaces thereof, said apparatus comprising: hanging means for hanging an upper edge side of a film or sheet on an upper edge portion of the mold surface of the injection mold; and an adsorbing device that adsorbs the film or sheet onto the mold surface of the injection mold through said upper and lower vacuum opening means disposed on the mold surface of the injection mold so as to interpose said hanging means therebetween from the upper and lower sides; wherein said respective upper and lower vacuum opening means extend along an upper edge of the mold surface of the injection mold.